Field of the Invention
The present disclosure relates to a rotor of a rotating electric machine.
Discussion of the Background
In an existing method for fixing permanent magnets to a rotor core of a rotating electric machine, the permanent magnets are inserted into permanent magnet insertion holes and fixed to the rotor core by injecting a resin into the permanent magnet insertion holes by injection molding (see, for example, Japanese Unexamined Patent Application Publication No. 2014-165938). However, if a gate vestige of the injection-molded resin protrudes from the rotor core, the gate vestige may become an obstacle in a subsequent step of assembling a rotor. Therefore, it is necessary to remove the gate vestige beforehand.
FIG. 6 illustrates a resin-sealing method for a rotor core described in Japanese Patent No. 4948040. In this method, a resin 114 is injected from a resin reservoir 113 of a die 112 into a resin sealing portion 111 of a rotor core 110, in which a permanent magnet 118 has been inserted into a permanent magnet insertion hole 117. In doing so, a cutout guide portion 116, which is connected to the resin sealing portion 111 and which accommodates a protrusion 119 of the die 112, is formed in steel sheets 115 of the rotor core 110; and the resin 114 is injected from the resin reservoir 113 into the resin sealing portion 111 through the cutout guide portion 116. After the resin 114 has solidified, a resin (cull) 129 that remains below a plunger 121 is broken off at a recess formed by the protrusion 119 by applying a force to the resin (cull) 129 outward in the radial direction, thereby preventing the resin 114 from protruding from a surface of the rotor core 110.
However, with the resin-sealing method for a rotor core described in Japanese Patent No. 4948040, in which the resin 114 is prevented from protruding from the surface of the rotor core 110 by breaking off the resin (cull) 129 at the cutout guide portion 116, the position at which the resin (cull) 129 is broken off may vary and the resin 114 may be broken off in such a way that the resin 114 protrudes from the surface of the rotor core 110. If the resin 114 protrudes from the rotor core 110, the resin 114 becomes an obstacle in the subsequent step of assembling a rotor. Moreover, if the resin 114 becomes detached and becomes a foreign object, the resin 114 may negatively affect the performance of the rotor, and therefore it is necessary to remove the resin 114 manually. As a result, extra work and time are needed, and the manufacturing cost is increased.